Hi Carl,

No need to apologize for such a well worded, detailed post. Especially with paragraphs! I'm not too familiar with the '87, but assume you have LH 2.2 FI and some version of the EZK ignition, in which case the sequence below should apply.

Also, you said: "I have turned on the ignition and grounded the 86/2 pin, and the relay closes energizing the 87/2 pin and powering up the fuel pump."

Did you try starting with 86/2 grounded? If spark is OK it should run. If no start, suspect ignition as outlined below.

Start-Run Sequence LH 2.0/2.2 Version

1) During starter cranking, the distributor Hall sensor sends timing pulses to Ignition Control Unit (ICU)

2-a) The ICU uses these Hall Sensor pulses to trigger the Ignition Coil (– terminal) to initiate timed sparks from the coil.
**[CARL, are you getting spark t the plugs when cranking? If not, the distributor Hall Switch or wiring are prime suspects. See 2-b below.]

2-b) At the same time, The ICU also propagates the pulses to the FI ECU, to allow FI operation (no ICU pulses means no Fuel pumping).
**[CARL, looking at a Mitchell diagram for the '88 740, this is the Yellow -Gray wire from ICU 17 to FI ECU 1.]

3-a) The Fuel Injection (System)* relay (previously energized at Key On) powers the AMM, IAC, ECU, Injectors, and Fuel (pump) relay coil + side.
* The LH 2.0 System relay is adjacent to the Fuel relay (same relay type).

3-b) When ICU pulses are received by the FI ECU, it "energizes" the Fuel relay by grounding the relay coil (– side) to run the fuel pumps.
**[CARL, this is a known failure on certain LH 2.2 240s ECUs. I think the last 3 digits in the Bosch # are 561. You might search your ECU # here for more info on this.]

When all these things work, the engine runs until the Ignition is switched off, which in turn shuts down the FI system.

Determining whether or not there is spark at the plugs (2a) — and whether or not the plugs are getting gas (3b) — makes a good no-start "starting" point.

For example, if 2a fails due to a bad Coil connection, there will be a no-start with gas-wet plugs. If 2b fails (practically never) [*** But maybe now for CARL?***] symptoms will be Fuel-related: a no-start with spark at the plugs, but plugs remain dry.


--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.